With the development of display technology, flat display devices of liquid crystal displays (LCD) and the like have advantages of high quality, energy saving, thin body and wide application range, etc., so the devices are widely applied to various consumer electronic products of cell phones, televisions, personal digital assistants, digital cameras, notebook computers, desktop computers and the like, and the devices become the mainstream display devices.
Most liquid crystal display devices in current market are backlight type liquid crystal display devices, which include liquid crystal display panels and backlight modules. The liquid crystal display panel is usually consisting of a color filter (CF) substrate, a thin film transistor (TFT) substrate, liquid crystal interposed between the CF substrate and the TFT substrate, and a sealant. However, the liquid crystal display panel of such structure often occurs a problem of poor alignment between the CF substrate and the TFT substrate, and the problem causes pixel light leakage, low aperture ratio or other issues. In order to overcome the said problems, a liquid crystal display panel of color filter on array (COA) structure is produced, and the COA technique is a technique that the color filter layer is prepared on the TFT substrate so as to form the CF. The liquid crystal display panel of the COA structure does not have the problem of alignment between the CF substrate and the array substrate, so difficulty of cell alignment process during display panel fabrication process can be reduced, deviation of cell alignment can be obviated, and thus black matrix can be designed as narrow linewidth to increase the aperture ratio.
Generally, the display principle of the liquid crystal display panel is that the backlight passes through the lower polarizer to form polarized light of polarization direction parallel to transmission axis of the lower polarizer. The polarized light passes through red, green and blue (RGB) color filter then to form tri-color polarized light of RGB. After the tri-color polarized light of RGB passed through the liquid crystal layer, the tri-color polarization direction thereof is adjusted, and the tri-color polarized light of RGB passes though upper polarizer (the liquid crystal display panel of the COA structure); or the tri-color polarized light of RGB passes the liquid crystal layer, then passes the RGB color filter layer to form the tri-color polarized light of RGB, and passes through the upper polarizer to emit light (the liquid crystal display panel of the common structure). No matter what kind the structure of liquid crystal display panel is, the liquid crystal layer therein acts as a valve for controlling light passing amount. The most important two factors of the display principle are the polarized light and RGB trichromatic.
Currently, due that a quantum dot (QD) which is excited by the backlight can emit light with characteristics of narrow wavelength (small half peak), bright color (high color density) and the like, a lot of technology focus on the application of the quantum dots in the liquid crystal display panel to enhance color saturation of the liquid crystal display panel. It is unlike the quantum dot that light emitted by a quantum rod (QR) can be polarized light; and a wavelength of the light emitted by the quantum rod can be controlled by controlling a diameter of the quantum rod.